Process of level dyeing of fibrous poly-acrylonitrile textiles with cationic dyestuffs

ABSTRACT

A method of dyeing a fibrous textile material composed of an acrylonitrile polymer in level shades with a cationic dye from an aqueous liquor by carrying out the dyeing at a predetermined temperature T which is dependent upon definite liquor exhaustion rates, a constant a which denotes the change in temperature which halves or doubles the liquor exhaustion rate measured at a dyeing temperature of 100* C and a constant b which denotes the depth of color to be achieved in milligrams of dye per gram of fibrous material.

United States Patent Mayer et al.

[54] PROCESS OF LEVEL DYEING OF FIBROUS POLY-ACRYLONITRILE TEXTILES WITH CATIONIC DYESTUFFS [72] inventors: Udo Mayer; Herbert Fleischer, both of Ludwigshafen, Germany Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen am Rhine. Germany 221 Filed: Dec.6, 1968 211 Appl.No.: 781,818

[73] Assignee:

[30] Foreign Application Priority Data Dec. 8, 1967 Germany ..P 16 19 376.3

[52] US. Cl. ..8/177 AB [51] [58] Field of Search ..8/177, 177 AB [56] References Cited UNlTED STATES PATENTS 2,955,009 10/1960 Pitts ..8/177 AB 2,978,290 4/1961 Bossard et a1. ..8/177 AB OTHER PUBLICATIONS J. Carbonell, Amer. Dyestuff Reporter, Nov. 7, 1966, pp. 71- 76 and 81 J. J. lannarone et a1., Amer. Dyestuff Reporter, Feb. 14, 1966,

T. Vickerstaff, The Physical Chemistry of Dyeing, 1954, Pub]. lnterscience Publishers Inc., New York, pp. 157- 160, TP893V5 1954 C2 T. Vickerstaff, The Physical Chemistry of Dyeing, (1954) Publ. lnterscience Publ. Inc. New York, pp. 142- 153, 161, 162.

Primary Iimminer-George F. Lesmes Assistant Examiner-T. J. Herbert, Jr.

Attorney-Johnston, Root, OKeeffe, Keil, Thompson & Shurtleff [5 7] ABSTRACT A method of dyeing a fibrous textile material composed of an acrylonitrile polymer in level shades with a cationic dye from an aqueous liquor by carrying out the dyeing at a predetermined temperature Twhich is dependent upon definite liquor exhaustion rates, a constant a which denotes the change in temperature which halves or doubles the liquor exhaustion rate measured at a dyeing temperature of 100 C and a constant b which denotes the depth of color to be achieved in milligrams of dye per gram of fibrous material.

3 Claims, 2 Drawing Figures 20 4O 6O 80 I00 PROCESS OF LEVEL DYEING F FIBROUS POLY- ACRYLONITRILE TEXTILES WITH CATIONIC DYESTUFFS' This invention relates to a new process for dyeing acrylonitrile polymers. 7

According to conventional methods of dyeing acrylonitrile polymers, an acid, a salt and a dye and, if necessary, a retarding agent are added to the dye liquor which is rapidly brought to a temperature corresponding to .the glass temperature of the fiber generally from 70 to 85C. The temperature is thereafter raised slowly anduniformly to 100C and the liquor is held at boiling temperature untilit is exhausted and good penetration of the fiber hasbeen achieved.

In this method it is a disadvantage that a long heating up period is necessary and that the temperature has to be increased with great care in order to prevent unevenness.

In the rapid-dyeing method described in Melliand Textilberichte, 49, 195 et seq. (1968) the difficulties occuring during the heating up'period are avoided by adding acid and salt to the liquor, rapidly bringing it to boiling temperature and only then adding the dye and any retarder needed. The entire dyeing process thus takes place at the boiling temperature. This method is only suitable however for dyeing equipment in which there is a particularly rapid liquor circulation because it is only thus that dye added at the boiling temperature can be quickly and homogeneously distributed in the dye liquor.

Another method of dyeing acrylonitrile polymer fibers is that known as the constant-temperature method. The retarder can be dispensed with in this method. Acid and salt are added to the liquor and it is brought to a temperature T which lies between 80 and 100C, depending on the depth of color required. As soon as this temperature is constant, the dye isadded and allowed to be absorbed.

The disadvantage of this method is that the experimental methods of determining Tare so inexact that it is not possible to give a specific temperature but only a wide temperature range. The inaccuracy of the methods of determining T is also shown by the fact that it is not possible to differentiate between dyes having different tinctorial behavior and that the experimental results make it seem that there is a linear dependence of the dyeing temperature on the depth of color to be achieved.

' The rate of absorption of cationic dyes is in fact so dependent on temperature that it is doubled or halved as a rule by a change in temperature of only 4C. It follows from this that in the constant-temperature method the usual indication of a temperature range is not exact enough and does not ensure reliable results.

We have now found that acrylonitrile polymer and copolymer textile material can be dyed level shades with cationic dyes by heating the liquor to the dyeing temperature T and carrying out the dyeing at this temperature at a defined rate of exhaustion, the temperature T being derived from the equation:

where:

a is the change in temperature which halves or doubles log b-log +2) definition of basic dyes see e.g. Color lndex,-Volume l, p.

Within the group of cationic dyes the compounds having an azacyanine system are of special importance.

There are several variants for dyeing at a defined rate of liquor exhaustion. For example the dye liquor to which acid tga(l00C is the depth of color to be achieved in mg of commercial dye per g offibrous materal dye per g of fibrous material X is the exhaustion of the liquor as a percentag I is the dyeing time in seconds appertaining to the liquor exhaustion X (X/ w/TQT is the rate of liquor exhaustion at the temperature T, and

tga( 100C) is equal to Cpl /7 C,- being the concentration of commercial dye in the fiber in mg per g which is present after the time t at a dyeing temperature of 100C.

The term commercial dye refers to a dye of commercial pu- (with or without salt) has been added and which already contains the textile material to be dyed may be heated to the dyeing temperature calculated according to equation (l) and then the dissolved dye added.

To avoid disturbances caused by temporary differences in concentration during addition of the ,dye, it may be advantageous to remove the textile material from the liquor, to add the dye and, as soon as it has been homogeneously dispersed, to return the textile material. To compensate for any fall in temperature occurring by heat radiation of the tex tile material, the liquor can be raised to an appropriately higher temperature prior to removal of the textile material.

For the singlebath bulking and dyeing of high bulk yarn according to the new process, the liquor to which acid (with or. without salt) has been added may be heated rapidly to boiling point and kept boiling until the yarn has been bulked. It is then cooled to the calculated temperature T, the dye is added and dyeing is carried out.

Finally it is also possible, as in the conventional methods, to add acid, salt and dye at a low temperature, to heat the liquor to the temperature T calculated according to equation (l) and to carry out dyeing at this temperature.

When the dyeing process at the temperature T calculated according to equation (1) is substantially over, the liquor may .either be cooled immediately, or'it may be heated to a higher temperature, for example 100C, to improve liquor exhaustion and penetration of the fiber. v

Unevenness arises from the fact that at different parts of the fibrous material the dye goes on at different rates owing to temperature and concentration differences of the dye in the liquor.

Unevenness is therefore the better prevented the more rapidly the liquor circulates in the equipment used. The probability of obtaining a level dyeing under given dyeing conditions is therefore dependent on the type of machine used. For example level dyeings may easily be obtained in cheese dyeing machines in which liquor circulation is good, but in the case of hank dyeing machines having slow liquid circulation it is often necessary to take special precautions to obtain a good result.

The new process offers the advantage over prior art methods that the liquor exhaustion rate can be adjusted for all dyeings with cationic dyes to an optimum value for given equipment. This value depends especially on the circulation of the liquor in the machine and can be so adjusted that the liquor is exhausted for example in 20, 30, or minutes or t o hours...

Another advantage of this process arises from the fact that the probability of obtaining a level dyeingis the same for all dyeing recipes provided dyeing is carried out at the same liquor exhaustion rate. When it has been established that in a particular machine a liquor exhaustion time of for example 60 minutes results in level dyeings, this liquor exhaustion time can be relied on to give level shades in all subsequent batches.

The equation (1) which is necessary according to the new process for ascertaining the dyeing temperature T is determined as follows: e

in dyeing polyacrylonitrile fibers it is necessary to distinguish between liquor exhaustion rate and rate of absorption. The rate of absorption is given by the equation (2):

C; being the concentration of dye in the fiber in mg of commercial dye per g of fibrous material; constant denoting fiber constant;

D denoting diffusion coefficient and t denoting time in seconds.

If in a coordinate system the concentration C; is plotted against {T a straight line is obtained whose inclination:

tga constant is a clear measure of the rate of absorption of the dye concerned. As may be seen from the equation, tga is independent of the concentration in the dye liquor and accordingly independent of the depth of color to be achieved.

In FIG. I of the drawing the absorption procejs for a dyeing whose depth of color is to be variable and is d noted by b is represented by such a straight line (see FIG. 1).

Since the amount of dye cannot exceed the value b, C rises linearly with /7 and finally becomes a straight line proceed ing parallel to the abcissa at a distance b.

If the amount of dye in parts absorbed is given by the expression (X:l00)-b and the dyeing time appropriate to this amount of dye is given by 1,, the equation (3) holds good according to FIG. 1:

X .L 4; T 100 where pl X= liquor exhaustion in t time for liquor exhaustion X b depth of color to be achieved in mg of commercial dye per of fiber (X 1,)T rate of liquor exhaustion at a temperature T, i.

e. the extent (in to which the liquor is exhausted after a certain time.

Equation (3) establishes a quantitative relation between absorption rate tga and liquor exhaustion rate (X/ {UT Having regard to the fact that tga is a dye constant independent of quantity, equation (3) shows that the liquor exhaustion rate has to decrease as the depth of color b increases, which agrees with experience in practice.

The rate of absorption of cationic dyes by polyacrylonitrile fibers is very dependent on temperature above the glass temperature. With some types of fiber a lowering of the temperature by only 3C is enough to halve the tga value. If the temperature is lowered by 6C, the tga value is quartered and upon lowering the temperature by 9C one eighth of the tga value results.

In order to find a quantitative expression for the dependence on temperature of the value tga to be determined at 100C, the question may be asked how often tga has to be halved in order to obtain the lower value tga (T), and this question formulated by an equation. Equation (4) follows from this:

tga( 100 C.) 2

CHQO

n the number of times tga has to be divided in halfin the lowering of the temperature from C to TC. Since a single halving of tga is brought about by a reduction in temperature of l X 3C (with a fiber having a temperature factor of 3C), a second halving by a reduction in temperature of 2 X 3C, halving by n times by a reduction in temperature of n X 3C,

A T= n x 3C 5 The value n in equation (4) may therefore be replaced by AT/3 and equation (6) is then obtained:

tga(100) qa (100) 2 2 (6) Having regard to equation (3) equation (7)15' then obtained:

l a T 2 which can be byreplacing the number 3 by a,

equation (8) being obtained:

K .L f T 100 2- a reduction in temperatur e which halves the tg a value of any given fiber. By solving for T, equation (1) is obtained from equation tga(100) a log By means of this equation it is possible to find for any given depth of color b a temperature T at which the liquor exhaustion rate (X/ {@T corresponds to the optimum value for given equipment. It is merely necessary to determine by experiment the value tga 100).

Equation (1) shows that at a given liquor exhaustion rate, parallel straight lines having an inclination of a/log 2 must be obtained if the dyeing temperature T is plotted against the depth of color b on the logarithmic scale. By means of these straight lines the temperature T may be determined for any combination of dyes.

A combination of 0.5 percent of dye 2 (5mg ofdye/g offiber) 0.7 percent ofdye 3 (7mg of dye/g offiber) 0.9 percent of dye 4 (9mg ofdye/g of fiber) will be given as an example with reference to FIG. 2 of the drawing.

The dyes have the following structural formulas and the straight lines in FIG. 2 hold good for a fiber having a 4 and the stated tga (100C) values:

Dye 3 tg a(100 C.) =0.03

( JHa CHaSO4 The temperature value for a 0.5 percent dyeing with dye 2 is first found and this valueis located on the straight line belonging to dye 3. ,A move is then made on the abscissa about 0.7 percent further and the temperature value obtained is entered on the straight line for dye 4 and then 0.9 percent is added to the abscissa. The ordinate value obtained is the dyeing temperature for the combination.

It is assumed that with respect to the liquor exhaustion rate 0.5 percent of dye 2 corresponds to 0.56 percent of dye 3, and 1.26 percent of dye 3 corresponds to 1.97 percent of dye 4 so that there is not objection to onedye being substituted for another.

-ln the same way as for dyes, it is possible in the case of cationic retarders or auxiliaries of similar constitution (which can be regarded as colorless dyes) to determine via the tga value at 100C a straight line which illustrates in dependence on the amount used the temperature required at a given liquor exhaustion rate.

From this it follows that it is alsopossible to determine the temperature to'be chosen for a combination of dye and retarder or cationic auxiliary at which a particular liquor exhaustion rate is present.

. Equation (13) can therefore be used to discover the temperature at which the optimum liquor exhaustion rate is present, by means'of a preliminary experiment in which the liquor exhaustion rate at the temperature T is determined.

in practice it has proved to be particularly favorable to determine the dyeing temperature for dye combinations by calculation, and it is most advantageous to reduce the amounts of dye to be used to a common reference magnitude. A straight line which reproduces the dyeing temperature in dependence on the amount used and which has been deter- By means of this straight line it is also possible to determine what amount of a cationic auxiliary has to be used as a thermoregulator with a given .dye combination in order to obtain a defined liquor exhaustion rate at a given dyeing temperature. This is of great importance when dyeing equipment having automatic temperature control is used because the number of temperature-time programs required can be kept low.

For example if it is certain that a liquor exhaustion rate of equation (9) at which the liquor is exhausted afiei-"fiiiiiites is sufficient mined fora thermoregulator is outstandingly suitable as a reference magnitude. For any given thermoregulator there is for every dye a factor by which the amount of dye has to be multiplied in order to discover the amount of thermoregulator corresponding to it in terms of the liquor exhaustion rate. In the case of combination dyeings it is only necessary to add the amounts of dye expressed as amounts of thermoregulator in order to obtain (with reference to the straight line which is specific for the' thermoregulator) the dyeing temperature required for agiven liquor exhaustion rate.

The invention is illustrated by the following Examples. Parts and percentages in the Examples are by weight.

EXAMPLE 1 One hundred parts of an acrylonitrile polymer cloth having I a value a 4 is dyed in an aqueous liquor containing four parts for level dyeing, then equation (10) holds good for all dyes I and all depths of color:

T=10o-- (log tg 0x100 -log b-log 1.67+2

7 log 2 For the general case, not starting from an established liquor exhaustion rate of 100/60 equation (1 1) holds:

' a. 100 1 b-lo firm Hg g u.

When equation l l is substracted from equation 12 T 100 Y equation 13) is obtained:

of dye 3 having a tga (100C) value of 0.93 and three parts of acetic acid at a liquor ratio of 12:1 and a temperature T of 98 The temperature T 98 C. results from the equation The, value 1.67 is the value of the quotient of the liquor exhaustion rate (X/ m assumingthat a 100 percent liquor exhaustion is achieved after 1 hour.

The liquor is first heated to 98C after which the dye solution is added. After a dyeing time of minutes, the liquor is exhausted and is cooled. The dyeing is excellently level.

EXAMPLE 2 One hundred parts of acrylonitrile polymer flock having a value a 3 is dyed in an aqueous liquor which contains two parts of dye 4 having a tga (100C) value of 1.66, three parts of acetic acid and 10 parts of Glauber's salt at a liquor ration of 15:1 and a temperature T of 92C calculated according to 50 the equation:

3 log T=100 (log 1.66-l og 20-log 1.36+2) The value 1.36 corresponds to a liquor exhaustion rate of 5 100/ 90.60 i.e. a dyeing time of minutes.

a 20 minutes. An excellently level dyeing IS obtained. Ts, wVT log 2 (log x Tw 10 /t l T) 0 p M rate which can be determined.

Equation.(l2) gives the dependence of liquor exhaustion EXAMPLE 3 One hundred parts of an acrylonitrile polymer cloth (a 4) is dyed in an aqueous liquor which contains:

0.5 part of dye 2 having a tga C) value of 0.8 l

0.7 part of dye 3 having a tga 100C) value of 0.93,

0.9 part of dye 4 having a tga 100C value of 1.48 and three parts of acetic acid at a liquor ratio of 20:1 and a temperature of 93.5C. The temperature is ascertained from the graph in FIG. 2 by the method described above.

The liquor is heated rapidly to 955C, the yarn is taken out from the liquor and the dissolved dyes are added; as soon as the dyes have homogeneously dispersed, the yarn is reintroduced. The liquor cools down to 935C. Dyeing is continued for 60 minutes at this temperature and the whole is then cooled. The dyeing obtained is excellently level.

One hundred parts of a high-bulk acrylonitrile polymer yarn (a 4) is dyed in an aqueous liquor which contains 0.5 part of dye 2 having a tga (100C) value of 0.81, 0.7 part of dye 3 having a tga (100C) value of 0.93, and three parts of acetic acid at a liquor ratio of 30:1 and a temperature of 91 C. The temperature is ascertained graphically analogously to Example 3.

The liquor is rapidly brought to 100C and the yarn is bulked for 5 minutes at this temperature. The whole is then cooled and the temperature is adjusted at 91C. The dissolved dyes are then added to the liquor. After a dyeing time of 60 minutes the exhausted liquor is cooled. The dyeing is excellently level.

EXAMPLE 5 One hundred parts of an acrylonitrile polymer cloth (a 4) is dyed in an aqueous liquor which contains 1.3 parts of a thermoregulator 1 having the formula EXAMPLE 6 One hundred parts of a mixture of 50 parts of an acrylonitrile polymer fiber (a 4) and 50 parts of cotton is dyed with 1 part of a dye having a tga (100C value of 0.93 and three parts of acetic acid at a liquor ratio of 50: land at a temperature of 93C calculated according to the equation:

4 T-100 T (lg 0.93-log 20-1og 1.36-1-2) I and a liquor exhaustion rate of 1.36.

The liquor has acetic acid and dye added at 60C and is then heated to 93C. After dyeing for 90 minutes at 90C the temperature is raised rapidly to 100C and kept there for 20 minutes. An excellently level dyeing is thus obtained.

EXAMPLE 7 One hundred parts of a fibre mixture of 50 parts of acrylonitrile polymer (a 4) and 50 parts of polyester is dyed with 0.2 part of dye 2 having a tga (100C) value of 0.81, 0.2 part of dye 3 having a tga (100C) value of 0.93 and three parts of acetic acid at a liquor ratio of 40:1 and at a temperature of 89C. The temperature is ascertained graphically as in Example 3.

The dyes and acid are added to the liquor adjusted to 89C. After 60 minutes the exhausted liquor is cooled. The dyeing is excellently level.

EXAMPLE 8 One hundred parts of an acrylonitrile polymer cloth (a is dyed with two parts of dye 4 having a tga (100C) value of 2.4 and three parts of acetic acid at a liquor ratio of 40:1 and at a temperature of 87C. The temperature is obtained from the following equation for a liquor exhaustion rate of 100/40.60= 2.05:

proved by heating the liquor for 10 minutes at 100C. An excellently level dyeing is thus obtained.

(10g 2.4-log -10,; 2.o5+2

EXAMPLE 9 T=+ g (log 1.67-log 1.05 =92 0.

EXAMPLE 10 To determine the'a value of an acrylonitrile polymer fiber of unknown origin, parts of this fibrous material is dyed at 100C and at 90C with 3 parts of dye 3 having a tga (100C) value which is not known for this fiber and three parts of acetic acid. From the measured liquor cxhuuslion rates X/m 100 c and urn/$90 c of 2.4 and 0.32 and by means ofthe equation:

( I! WZ) log 2 log log 1 vi.

the value for a is found to be:

(100-90) -log 2 log 2.4log 0.32

What we claim is:

l. A process for the level dyeing of an acrylonitrile polymer fibrous textile material with a cationic dye in an aqueous liquor which comprises heating the liquor to a predetermined dyeing temperature Tand dyeing the textile material with said cationic dye at this temperature at a defined liquor exhaustion rate, the temperature Tbeing determined by the equation a o T 100E (log tga(100 C.)

X logb-lo +2) vr. T wherein:

0 denotes a constant for each specific fiber of about 3 to 5 which is the change in temperature which halves or doubles to at (100C b denotes the depth of color (in mg. of said cationic dye per g of fibrous material) to be achieved;

X denotes the liquor exhaustion in r. denotes the dyeing time in seconds which corresponds to the li uor exhaustion X;

(X/ 1,)T denotes the liquor exhaustion rate at the temperature T; and

tg a 100) C;/ JTwherein C; denotes the concentration of said cationic dye in the fiber in mg per g which is present in the fiber after the time t at a dyeing temperature of 100C.

2. A process as claimed in claim 1 which includes the step of using the value of T, where the value of tga (100) of a cationic dye for a specific fiber is not known, by dyeing said specific fiber with the cationic dye at an arbitrarily chosen temperature T and then determining the temperature Tfrom the equation where (X/ 1,)T denotes the liquor exhaustion rate at the temperature T to be measured and (X/ 113T is defined as in c aim 1.

(Tm-T g) log 2 wl a w2 in which M 13 an WE denote the liquor exhaustion rates which are measured at the arbitrarily chosen temperatures T and T and where X and I t are defined as in claim 1.

mg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 5,658,461 Dated April 25, 1972 Invehtofls) Udo Mayer and Herbert Fleischer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lines 65 to 67,

"tg'o((lOOC is the depth of color to be achieved in mg of" commercial dye per g of fibrous materal I dye per g of fibrous material should read tg ((lOOC) b is the depth of color to be achieved in mg of commercial dye per g of fibrous material Column 8, line 24," "100 c" should read 100 0 line 24, 90 C" should read 90 C line 5 claim 1 "to 0Q should read 13gb Signed and sealed this 3rd day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patents 

2. A process as claimed in claim 1 which includes the step of using the value of T, where the value of tg Alpha (100*) of a cationic dye for a specific fiber is not known, by dyeing said specific fiber with the cationic dye at an arbitrarily chosen temperature Tw and then determining the temperature T from the equation where (X/ Square Root tx)Tw denotes the liquor exhaustion rate at the temperature Tw to be measured and (X/ Square Root tx)T is defined as in claim
 1. 3. A process as claimed in claim 1 which includes the step of determining the value of the constant a of a specific fiber by dyeing with said cationic dye at two arbitrarily chosen temperatures Tw1 and Tw2 and using an a from the equation in which (X/ Square Root tx)Tw1 and (X/ Square Root tx)Tw2 denote the liquor exhaustion rates which are measured at the arbitrarily chosen temperatures Tw1 and Tw2 and where X and tx are defined as in claim
 1. 